As he did at Audio Alchemy, Dusty Vawter continues to offer upgraded stand-alone power supplies for his CIAudio components. The previously reviewed VHP-1 headphone amp can be gussied up with the same-sized, same-styled VAC-1 to advance beyond its stock wall wart. An umbilical then connects the VHP-1's AC input socket to the output of the external power supply which itself plugs into the wall as any regular component would.

Housed in the same 4.4" x 2.65" x 4.4" WxHxD extrusion as the amp, the transformer-driven power supply outputs 14VAC @ 1.44 amps and includes an internal voltage switch and IEC power inlet to allow after-market cord swapping. Theory predicted increased drive into more challenging headphone loads, buffer bass, butcher dynamics and perhaps even a skoch of added warmth and heft. Having Senn 650s and AT W-1000s on hand, I assumed that the Japanese cans would benefit less if at all from the beefier supply while the German 'phones would most definitely go higher on the spiked juice. Swapping between the VAC-1 and stock supply was child's play and could nearly be done without interrupting the music. I was all set for Dusty's follow-up report on the strapped double decker versus going solo. What did I hear?

First off, chip-based amplifiers like the 47labs GainCard and its various commercial so-called clones under the Audio Zone and Audio Sector brands -- as well as Dusty's own take on one such speaker-driving amp in his CIAudio lineup -- have clearly shown that this approach is very viable. Hi-tech miniaturization of circuitry inside a small chip means less additional stuff becomes necessary to build a complete amplifier. Chassis get smaller and lighter, manufacturing costs go down and performance -- within the power ratings of said chips -- is directly competitive with more conventional amps as long as you use the right speakers.

Pick behemoths, leviathans or just plain nasty loads and massive Class A amps that double power into lower impedance still reign supreme. But into a copasetic load, there's no longer a need for that kind of excessive amplifier design. Small and light can do it just as well.

My exposure to chip amps (47labs Shigaraki, Audio Zone AMP-1, Ray Samuels Audio SR-71 headphone amp and now Dusty Vawter's VHP-1) suggest a common sonic thread. It's akin to tubes in image density, body and modest warmth. These amps don't sound like tubes but mimic certain parameters without the heat and wear characteristics of tubes nor any of their rolling options (which can be fun and costly). Chip amps can thus be very attractive to would-be tube lovers by offering a goodly portion of their qualities without the maintenance and prospective cost hurdles.

Adding the outboard power supply here worked in a domain very similar to adding a good active preamp into a system that previously ran source-direct. It's a compliment to the execution of the stand-alone amp that the scale of improvements into an easy load like my audio-technicas was modest only. This ties directly to my earlier statement that if you pick your loads smartly (speakers in general, headphones in this case), the old religion of the overbuilt power supplies no longer applies. While there were slight gains in bass control and midrange heft on more demanding material, I overall felt that I got 95% of the duo's performance from the single box and that those 5% only suggested themselves occasionally.

It's with the Sennheiser HD-650s that the true raison d'être of the VAC-1 asserts itself. Now the performance delta was of far more pronounced magnitude and revolved around the core qualities of better control and drive. Think firmer, more articulated bass, a more fully fleshed-out midrange and sweeter highs. Then add more pronounced dynamic swings, an area where the W-1000s beat out the Sennheisers but where the add-on power supply nearly closed the gap. If it's life and excitement you're after, the VAC-1 becomes mandatory on the Sennheisers and diminished returns on the audio-technicas. At $159 for the second box, we're in a very comfortable zone either way and being able to do the upgrade in two steps is only further incentive to go full hog. On-line commentary on the 650s seems rather mixed, spanning the gamut from "world's best headphones (shy of the insane stuff)" to far more lukewarm reactions.

Count me among the latter. However, my regard for the 650s moves way up when what drives them seems fully up to the task. I then still prefer the ATH W1000s but I can also understand how different listener preferences could go the other way. If you're a Sennie and $500 for a dedicated headphone amp is in your ballpark, the CIAudio combo should be on your list. You'll get a peculiar feel of silk that's coupled to very good weight, substantial images, no transistor flatness or chalkiness, natural highs and the kind of bass control you expect from solid-state. PRat is very good but never intense by way of exaggerated transients or hyped incisiveness. The core signature is one of dynamic verve, modest warmth and a very obvious and becoming texture of smoothness and elegance, nearly like a subliminal sheen à la satin paint finish - one up from flat, one down from semi-gloss.

While not as lush as a 6SN7 tube amp, the chip-amp signature of warmth+drive makes for very fetching vocals. Arguably most important of all, there's nothing about this two-piece amplifier that eventually creeps into your enjoyment to spell fatigue or effort. With the outright explosion of dedicated headphone amps in the market, the somewhat demure cosmetics of CIAudio's offering might be upstaged by wooden cheeks, gleaming chrome, glowing bottles or colorful anodizing - but it would be a serious mistake to overlook the VHP-1/VAC-1 combo. It's affordable price tag should suggest nothing else but smart engineering choices and cost-conscious cosmetic minimalism. After all, the most common headphones do not present such punishing loads that 25lbs monster amps become relevant. Whatever has a 1/4" plug on its tail will be perfectly copasetic with the CIAudio amp. If you insist on heavier, bigger and more expensive, indulge your beliefs but know that you're being excessive. The curve of diminishing returns hangs a really sharp right just past today's boxes. That means the smart shopper will be perfectly happy not going any farther...